Studies of diamond-like carbon (DLC) films deposited on stainless steel substrate with Si/SiC intermediate layers

In this work, diamond-like carbon （DLC） films were deposited on stainless steel substrates with Si/SiC intermediate layers by combining plasma enhanced sputtering physical vapour deposition （PEUMS-PVD） and microwave electron cyclotron resonance plasma enhanced chemical vapour deposition （MW-ECRPECVD） techniques. The influence of substrate negative self-bias voltage and Si target power on the structure and nano-mechanical behaviour of the DLC films were investigated by Raman spectroscopy, nano-indentation, and the film structural morphology by atomic force microscopy （AFM）. With the increase of deposition bias voltage, the G band shifted to higher wave-number and the integrated intensity ratio ID/IG increased. We considered these as evidences for the development of graphitization in the films. As the substrate negative self-bias voltage increased, particle bombardment function was enhanced and the sp^3-bond carbon density reducing, resulted in the peak values of hardness （H） and elastic modulus （E）. Silicon addition promoted the formation of sp^3 bonding and reduced the hardness. The incorporated Si atoms substituted sp^2- bond carbon atoms in ring structures, which promoted the formation of sp^3-bond. The structural transition from C-C to C-Si bonds resulted in relaxation of the residual stress which led to the decrease of internal stress and hardness. The results of AFM indicated that the films was dense and homogeneous, the roughness of the films was decreased due to the increase of substrate negative self-bias voltage and the Si target power.

Nanomechanical and Electrochemical Properties of Diamond-Like Carbon (DLC) Films Deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) Technique

Diamond-like carbon （DLC） films was deposited successfully on stainless steel sub- strates with Si/SiC intermediate layers by combining plasma enhanced unbalanced magnetron sputtering physical vapor deposition （PEUMS-PVD） and microwave electron cyclotron resonance plasma enhanced chemical vapor deposition （MW-ECR PECVD） techniques. The effect of sil- icon dopant on the structure, morphology, nanomechanical properties and electrochemical be- havior of DLC films were investigated by Raman spectroscopy, nano-indentation, atomic force microscopy （AFM） and potentiodynamic method and electrochemical impedance spectroscopy （EIS）. It showed that the incorporated silicon atoms substituted sp2-bonded carbon atoms in the ring structures, promoting the formation of sp3-bonds. The structural transition from C-C to C-Si bonds resulted in the relaxation of the residual stress, leading to the decrease in films hardness. The DLC films with Si/SiC intermediate layers led to significant improvement in the corrosion resistance of the stainless steel substrate due to effective isolation and good chemical inertness of the DLC films.

Study of relationship between structure and transmittance of diamond-like carbon (DLC) films

In this paper, the transparent hard diamond-like carbon (DLC) films were deposited on glass substrate by magnetic confined radio-frequency plasma chemical vapor deposition. The structure of films was studied by Raman spectra and X-ray photoelectron spectra (XPS), the transmittance of films by Spectrophotometer. The mechanism of the influence of films structure on transmittance of the films was discussed. The results show that the thickness of films was lower than 100nm, and the transmittance was over 90% in 380-780 nm region. Discussion in theory on the influence of film structure on transmittance was correspondence to experiment results.

STUDY ON DIAMOND LIKE CARBON THIN FILM BY FILTERED VACUUM ARC DEPOSITION

Diamond like carbon thin film is successfully deposited on silicon, titanium and stainless steel substrate at low temperature in a filtered vacuum arc deposition system. Arc discharges are established on a graphite cathode in the system with a toroidal macroparticle filter. A cathode activating magnetic field and a filtered magnetic field to collimate the plasma beam are applied. Ion current convected by the plasma beam is measured with a negatively biased probe. It is shown that the magnetic field of the coils located on the plasma duct has a strong influence on cathode spot behavior. Orthogonally the designed experiments are carried out to optimize the deposition parameters of arc stability. Finally, the diamond like carbon thin films are studied by scanning electron microscope (SEM) and Raman spectrum.

熔融温度对DLC薄膜杂化状态影响的分子动力学研究

文章基于Tersoff势函数,采用分子动力学方法建立金刚石的分子模型,分析了不同熔融温度和冷却过程对原子键合结构,径向分布函数曲线和配位数的影响,从原子尺度阐明了DLC薄膜制备过程中原子形态杂化的形成机理。研究发现:DLC薄膜主要由C-sp3和C-sp2杂化相组成,当温度低于6000 K时,熔融和冷却基本不会使C-sp3杂化发生结构转变,薄膜的性能比较稳定。当温度高于7000 K时,熔融过程中有大量的C-sp3杂化原子转变为C-sp2和C-sp1,冷却和弛豫平衡会引起高能态C-sp3杂化原子转变为C-sp2,但C-sp1杂化的含量基本不变。熔融温度主要影响DLC薄膜制备过程中C-sp3和C-sp2相的百分比含量,当体系中C-sp2含量超过40%,薄膜的性能将趋向于石墨。

退火温度对DLC和Si-DLC涂层微观结构和摩擦学性能的影响

类金刚石(DLC)涂层因具有优异的减磨耐摩性能被广泛应用,而涂层内部存在较高的内应力这一缺点限制其在摩擦学领域的进一步应用。退火处理可以通过改变涂层微观结构来降低涂层内应力,从而提高涂层的摩擦学性能。为研究退火温度对DLC和硅掺杂类金刚石(Si-DLC)涂层微观结构和摩擦学性能的影响,采用等离子体增强化学气相沉积(PECVD)和电弧离子镀的复合沉积技术制备DLC和Si-DLC涂层,将涂层在大气环境中进行不同温度的退火处理。运用扫描电子显微镜、高分辨率透射电子显微镜、拉曼光谱以及XPS光谱仪对涂层摩擦试验前后的形貌和结构进行表征,采用纳米压痕仪和摩擦磨损试验机测试涂层的力学性能和摩擦学性能。结果表明:沉积的DLC和Si-DLC涂层为非晶结构。退火温度对涂层的微观结构和摩擦学性能有重要影响。随着退火温度从RT上升到500℃,由于C-H键断裂,C网发生集束化,DLC涂层的sp^(3)含量呈现先上升后降低的趋势,涂层的sp^(3)含量在300℃热处理后获得最大值,涂层硬度达到最大的20.66 GPa;而Si-DLC涂层由于Si元素的掺杂提高了涂层的热稳定性,其在400℃热处理时sp^(3)含量最大,硬度最大值为24.28 GPa。涂层与氧化锆对磨球的磨损机理为磨粒磨损,涂层的磨损率呈现先降低后升高的趋势,热处理温度为300和400℃为最优。研究证明涂层的微观结构和摩擦学性能可以通过热处理温度调控,优选热处理温度的涂层具有优异的综合性能。研究结果可为退火处理对DLC和Si-DLC涂层的性能影响提供理论支持。

Ti-DLC薄膜压阻性能及载流子输运行为研究

围绕压阻传感器领域对高性能类金刚石(Diamond Like Carbon,DLC)薄膜压阻敏感材料的需求,针对金属掺杂DLC存在的载流子输运行为和实际多工况(如温度、湿度等)下压阻性能不明的问题,本工作以Ti-石墨复合拼接靶为靶材,采用高功率脉冲磁控溅射技术,高通量制备出4种Ti含量(原子分数为0.43%~4.11%)的Ti掺杂类金刚石(Ti-DLC)薄膜,研究了Ti含量对薄膜组分结构、电学性能、变湿度环境下压阻性能的影响规律。结果表明:Ti含量(原子分数)在0.43%~4.11%范围内,掺杂Ti原子均以固溶形式均匀镶嵌于非晶碳网络中,Ti-DLC薄膜电学行为表现为典型半导体特性,在200~350 K温度范围内,薄膜电阻率均随温度升高而降低。载流子传导机制在200~270 K内为Mott型三维变程跳跃传导,在270~350 K范围内则为热激活传导。Ti-DLC薄膜压阻系数(Gauge Factor,GF)最大值为95.1,在20%~80%相对湿度范围内,所有样品GF均随湿度增加而增大,这可能是引入的固溶Ti原子缩短了导电相之间的平均距离,同时吸附表面水分子导致电阻变化。

硅氧共掺DLC薄膜的制备及阻隔性能研究

目的研究硅(Si)、氧(O)元素掺杂对类金刚石(Diamond like Carbon,DLC)薄膜沉积、结构、表面形貌以及阻隔性能的影响,为高效制备高阻隔硅氧共掺类金刚石(Si and O Incorporated DLC,Si/O-DLC)薄膜提供新的思路参考。方法利用微波等离子体化学气相沉积(Plasma Enhanced Chemical Vapor Deposition,PECVD)技术在聚对苯二甲酸乙二醇酯(Polyethylene terephthalate,PET)基底表面沉积Si/O-DLC薄膜,具体研究反应单体中六甲基二硅氧烷(Hexaethyldisiloxane,HMDSO)含量对薄膜沉积和阻隔性能的影响。通过台阶仪、傅里叶红外光谱(FTIR)、X射线光电子能谱(XPS)、原子力显微镜(AFM)表征薄膜厚度、结构和微观形貌,并通过测试氧气透过率表征复合薄膜的阻隔性能。结果随着混合气体中HMDSO含量增加,薄膜的沉积速率提高,不同高度位置上沉积速率波动变弱,平均沉积速率最高达到310 nm·min^(–1),同时,薄膜中Si、O元素含量增加,相关的键合结构含量增加,薄膜表面致密性变差,氧气阻隔性能变弱;当HMDSO流量控制在1 mL·min^(–1)时,PET薄膜的氧气透过率可从未涂覆时的132mL·m^(2)·d^(–1)降低至2mL·m^(2)·d^(-1),阻隔性能明显改善。结论在一定工艺条件下,通过微波PECVD技术在PET薄膜表面涂覆Si/O-DLC薄膜,可明显改善其阻隔性能。

Synthesis and Characteristics of Diamond-like Carbon Films Deposited on Quartz Substrate

Diamond-like carbon (DLC) films are deposited on quartz substrate using pure CH4 in the surface wave plasma equipment. A direct current negative bias up to -90 V is applied to the substrate to investigate the bias effect on the film characteristics. Deposited films are characterized by Raman spectroscopy, infrared (IR) and ultraviolet-visible absorption techniques. There are two broad Raman peaks around 1340 cm-1 and 1600 cm-1 and the first one has a greater sp3 component with an increased bias. Infrared spectroscopy has three sp3 C-H modes at 2852 cm-1, 2926 cm-1 and 2962 cm-1, respectively and also shows an intensity increase with the negative bias. Optical band gap is calculated from the ultraviolet-visible absorption spectroscopy and the increased values with negative bias and deposition time are obtained. After a thermal anneal at about 500℃ for an hour to the film deposited under the bias of-90 V, we get an almost unchanged Raman spectrum and a peak intensity-reduced IR signal, which indicates a reduced H-content in the film. Meanwhile the optical band gap changed from 0.85 eV to 1.5 eV.

Characterization of the Diamond-like Carbon Based Functionally Gradient Film

Diamond-like carbon coatings have been used as solid lubricating coatings in vacuum technology for their good physical and chemical properties. In this paper, the hybrid technique of unbalanced magnetron sputtering and plasma immersion ion implantation (Plll) was adopted to fabricate diamond-like carbon-based functionally gradient film, N/TiN/Ti(N,C)/DLC, on the 304 stainless steel substrate. The film was characterized by using Raman spectroscopy and glancing X-ray diffraction (GXRD), and the topography and surface roughness of the film was observed using AFM. The mechanical properties of the film were evaluated by nano-indentation. The results showed that the surface roughness of the film was approximately 0.732 nm. The hardness and elastic modulus, fracture toughness and interfacial fracture toughness of N/TiN/Ti(N,C)/DLC functionally gradient film were about 19.84 GPa, 190.03 GPa, 3.75 MRa.m1/2 and 5.68 MPa.m1/2, respectively. Compared with that of DLC monolayer and C/TiC/DLC multilayer, this DLC gradient film has better qualities as a solid lubricating coating.

Preparation of H-terminated and aminated diamond like carbon surfaces

H-terminated DLC layers were synthesized on SiO 2 substrate by radio frequency (RF) magnetron plasma-enhanced chemical vapor deposition (PECVD) in a conventional reactor using C 4 H 10 as carbon source. As-deposited DLC films were characterized by Raman spectroscopy, scanning electron microscopy (SEM) as well as atomic force microscopy (AFM). The chemical reactivity of the obtained DLC surface was further investigated by exposing the photochemically oxidized DLC surface to a silane reagent. The course of the reaction was followed using water contact angle and X-ray photoelectron spectroscopy.

Micro/Nanomechanical and Tribological Properties of Thin Diamond-Like Carbon Coatings

The diamond-like carbon (DLC) films with different thicknesses on 9Crl8bearing steels were prepared using vacuum magnetic-filtering arc plasma deposition. Vickersindentation, nanoin-dentation and nanoscratch tests were used to characterize the DLC films with awide range of applied loads. Mechanical and tribological behaviors of these submicron films wereinvestigated and interpreted. The hardnesses of 9Cr18 and DLC. determined by nanoindentation, areapproximately 8GPa and 60GPa respectively; their elastic moduli are approximately 250GPa and 600GParespectively. The friction coefficients of 9Cr18, DLC, organic coating, determined by nanoscratch,are approximately 0. 35, 0. 20 and 0. 13 respectively. It is demonstrated that nanoindentation andnanoscratch tests can provide more information about the near-surface elastic-plastic deformation,friction and wear properties. The correlation of mechanical properties and scratch resistance of DLCfilms on 9Cr18 steels can provide an assessment for the load-carrying capacity and wear resistance.

B_(4)C&H-DLC薄膜在过氧化氢溶液中的摩擦学行为研究

采用闭合场非平衡磁控溅射技术在316L不锈钢表面沉积硼、氢掺杂类金刚石碳(B_(4)C&H-DLC)薄膜,利用扫描电镜(SEM)、Raman、X射线光电子能谱仪(XPS)、纳米压痕和线性往复摩擦试验机等系统分析了B_(4)C&H-DLC薄膜的结构、力学性能及过氧化氢水溶液中与不同对偶球的摩擦学行为.结果表明:B_(4)C&H-DLC薄膜在过氧化氢环境中与Al_(2)O_(3)球相对摩擦时,有严重的磨粒磨损行为,摩擦系数与磨损率较高.此外,B_(4)C&H-DLC薄膜在过氧化氢环境中与Si_(3)N_(4)和SiC球相对摩擦时发生了复杂的摩擦化学反应,形成了硅胶和硼酸的摩擦化学产物,发挥了减摩抗磨作用[磨损率较低分别为0.8×10^(-7)和1.0×10^(-7)mm^(3)/(N·m)].因此,本研究为碳基薄膜在氧化条件下摩擦副的合理设计和应用提供了试验依据,同时也为保护在苛刻环境工作的机械部件提供了1种可行方法.

Preparation of Diamond-like Carbon Films on the Surface of Ti Alloy by Electro-deposition

In this paper, diamond-like carbon (DLC) films were deposited on Ti alloy by electro-deposition. DLC films were brown andcomposed of the compact grains whose diameter was about 400 nm. Examined by XPS, the main composition of the filmswas carbon. In the Raman spectrum, there were a broad peak at 1350 cm^(-1) and a broad peak at 1600 cm^(-1), which indicatedthat the films were DLC films.

TiN/DLC和NiN/DLC涂层的组织结构及摩擦磨损性能

采用磁控溅射沉积技术在316L不锈钢基体上分别沉积了以TiN和NiN为过渡层的类金刚石(Diamond-like carbon,DLC)涂层。采用扫描电镜、拉曼光谱仪、纳米压痕仪、划痕测试仪和摩擦磨损试验机分析了DLC涂层的表面质量、组织结构和摩擦磨损性能。结果表明:NiN/DLC涂层表面颗粒及孔洞等沉积缺陷数量多,Ni和N共同沉积作为中间过渡层时,Ni多以金属单质的形式存在于DLC和基体之间,而由于金属基体结构及Ni的存在,提高了基体和过渡层间的界面匹配性,使得NiN/DLC涂层膜基结合强度高,接合力达到14.91 N;但Ti与N共同沉积作为过渡层时,Ti和C结合形成金属碳化物存在于DLC和基体之间,这有利于涂层密度(1.929 g/cm 3)和硬度的提高;而且高硬度金属碳化物的形成也有利于涂层变形能力的改善,并利于DLC结构的非晶化及促进sp 3-C键的形成。磨擦磨损分析则表明,无论是在干摩擦、去离子水中还是弱酸(pH=5.6的HCl溶液)工况下,NiN/DLC涂层由于硬度低、组织密度低导致涂层的抗摩擦磨损能力和耐腐蚀能力差;而TiN/DLC涂层具有更低的磨擦系数和磨损量,耐磨、抗磨和耐蚀性能优异。以上实验分析说明具有更高硬度的Ti的氮化物和碳化物作为过渡层能够更好地改善DLC涂层结构和摩擦磨损性能,而Ni为过渡层能够有效提高NiN/DLC涂层的膜基结合强度,但涂层磨擦过程中容易脱落失效。

DLC膜对金刚石纳米柱NV色心发光收集强度的影响

金刚石氮空位(NV)色心发光收集强度的提高是实现单光子源技术的关键。本工作将锥状的类金刚石(DLC)梯度减反膜引入纳米柱色心单光子源中,旨在从色心的自发辐射速率与光子收集效率两方面提高NV色心的发光收集强度。采用时域有限差分(FDTD)法对带有DLC膜的金刚石纳米柱复合结构进行了光学仿真,探究了不同结构参数的DLC薄膜对金刚石纳米柱NV色心光子收集强度、出射效率及自发辐射速率的影响,并且通过优化得到了最大收集强度下的结构参数。仿真结果表明,引入DLC膜能够使金刚石纳米柱中NV色心获得更高的光子出射效率(≥1%),并且能够改变纳米柱内部电场分布,使色心自发辐射速率增加16.8%,最终使光子的总收集强度增加15.5%。

Effects of Adsorption of Albumin and Gamma-Globulin on the Tribological Performance of a Diamond-Like Carbon Film

The effects of surface adsorption of bovine serum albumin(BSA) and human gamma-globulin(HGG) on the tribological performance of a DLC film were investigated using a quartz crystal microbalance with dissipation(QCM-D), a ball-on-disk reciprocating tribometer, and a three-electrode electrochemical cell. The results showed that the wear depth in the BSA solution was higher than that in the HGG solution. In the HGG solution, the HGG-adsorbed layer could act as a lubricating layer and protect the DLC film from wear. The wear volume of DLC film in BSA and HGG mixture solution was higher than that in single HGG solution. This may be because the BSA molecules inhibit the formation of HGG adsorbed layer during sliding.

Structures of Diamond-Like Carbon Films

The structures of diamond-like carbon （DLC） films, including a-C：H, a-C, ta-C：H and ta-C films have been investigated as a random covalent network with a dense film structure. The results show that sp2 C in a-C：H and a-C films tends to form olefinic and aromatic groups while sp^3 C in ta-C：H and ta-C films tends to form single or multiple sixfold groups. The hydrogen atoms in hydrogenated DLC films contribute to stabilizing the carbon skeletal networks. The film structures are well related to their properties such as optical gaps, density and hardness. The results also indicate that the high density and the extreme hardness of ta-C films are attributed to the forming of large sp^3 C bonded sixfold groups.

Deposition of Diamond-Like Carbon on Inner Surface by Hollow Cathode Discharge

A cylindrical hollow cathode discharge （HCD） in CH4/Ar gas mixture at pressure of 20-30 Pa was used to deposit diamond-like carbon （DLC） films on the inner surface of a stainless steel tube. The characteristics of the HCD including the voltage-current curves, the plasma im- ages and the optical emission spectrum （OES） were measured in Ar and CHn/Ar mixtures. The properties of DLC films prepared under different conditions were analyzed by means of Raman spectroscopy and scanning electron microscopy （SEM）. The results show that the electron exci- tation temperature of HCD plasma is about 2400 K. DLC films can be deposited on the inner surface of tubes. The ratio of sp3/sp2 bonds decreases with the applied voltage and the deposition time. The optimizing CH4 content was found to be around CH4/Ar =1/5 for good quality of DLC films in the present system.

Tribological properties of diamond-like carbon films deposited bv pulsed laser arc deposition

A novel method, pulsed laser arc deposition combining the advantages of pulsed laser deposition and cathode vacuum arc techniques, was used to deposit the diamond-like carbon （DLC） nanofilms with different thicknesses. Spectroscopic ellipsometer, Auger electron spectroscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, scanning electron microscopy and multi-functional friction and wear tester were employed to investigate the physical and tribological properties of the deposited films. The results show that the deposited films are amorphous and the sp2, sp3 and C-O bonds at the top surface of the films are identified. The Raman peak intensity and surface roughness increase with increasing film thickness. Friction coefficients are about 0.1, 0.15, 0.18, when the film thicknesses are in the range of 17-21 nm, 30-57 nm, 67-123 nm, respectively. This is attributed to the united effects of substrate and surface roughness. The wear mechanism of DLC films is mainly abrasive wear when film thickness is in the range of 17-41 nm, while it transforms to abrasive and adhesive wear, when the film thickness lies between 72 and 123 nm.